Climate Change: Impact On Human Health

Global Warming and Health Risks

Medical and public health groups are banding together to explain how global warming has taken a toll on human health and will continue to cause food-borne illnesses, respiratory problems, and deaths unless policy changes are enacted.

In a conference call with reporters, the heads of the American Medical Association (AMA) and the American Public Health Association (APHA) joined with a pediatrician and a scientist to lay out what they say is a major public health issue: climate change caused by global warming.

The "evidence has only grown stronger" that climate change is responsible for an increasing number of health ills, including asthma, diarrheal disease, and even deaths from extreme weather such as heat waves, said Dr. Georges Benjamin, executive director of the APHA.

For one, rising temperatures can mean more smog, which makes children with asthma sicker, explained pediatrician Dr. Perry Sheffield, assistant professor in the Department of Pediatrics and the Department of Preventive Medicine at the Mount Sinai School of Medicine, in New York.

There is also evidence that pollen season is also getting longer, she said, which could lead to an increase in the number of people with asthma.

Climate change also is thought to lead to increased concentrations of ozone, a pollutant formed on clear, cloudless days. Ozone is a lung irritant which can affect asthmatics, those with chronic obstructive pulmonary disease, and those with heart disease, said Dr. Kristie Ebi, who is a member of the Intergovernmental Panel on Climate Change.

More ozone can mean more health problems and more hospital visits, she said.

Aside from air-related ailments and illnesses, extreme weather can have a devastating effect on health, Sheffield said.

"As a result of global warming, extreme storms including hurricanes, heavy rainfall, and even snowstorms are expected to increase," Sheffield said. "And these events pose risk of injury and disruption of special medical services, which are particularly important to children with special medical needs."

Extreme heat waves and droughts are responsible for more deaths than any other weather-related event, Sheffield said.

The 2006 heat wave that spread through most of the U.S. and Canada saw temperatures that topped 100 degrees. In all, 450 people died, 16,000 visited the emergency room, and 1,000 were hospitalized, said Dr. Cecil Wilson, president of the AMA.

Climate change has already caused temperatures to rise and precipitation to increase, which, in turn, can cause diseases carried by tics, mosquitoes, and other animals to spread past their normal geographical range, explained Ebi.

For instance, Lyme disease is increasing in some areas, she said, including in Canada, where scientists are tracking the spread of Lyme disease north.

Ebi also recounted the 2004 outbreak of the leading seafood-related cause of gastroenteritis, Vibrio parahaemolyticus, from Alaskan seafood, which was attributed to increased ocean temperatures causing infected sea creatures to travel 600 miles north.

Salmonella outbreaks also increase when temperatures are very warm, Sheffield said.

Your Health and Three Key Factors Related to Climate Change

LA Smog AIR. We're used to thinking of industrial and traffic pollution as having a detrimental effect on air quality. But all other things being equal, rising temperature by itself increases the amount of ground-level ozone, a major constituent of smog. So many studies have linked higher ozone levels to death rates from heart and lung ailments that many cities issue smog alerts to warn those at risk to stay indoors. You can expect more and longer alerts.

WATER. Residents of the U.S. Gulf Coast don't have to be reminded that water can be a killer. You can usually evacuate people ahead of a major storm, but you can't evacuate infrastructure. "Thirteen of the 20 largest cities in the world happen to be located at sea level," says Dr. Cindy Parker of the Johns Hopkins School of Public Health in Baltimore, Md. That means that where people are most at risk from floods, so are hospitals and water-treatment plants. As we have seen in New Orleans, the health effects of losing those facilities persist long after the water has receded.

INSECTS. The news here is not all bad. Ticks, for example, may not be able to survive hotter temperatures in the southwestern U.S. And global warming is unlikely to have much of an effect on malaria, as long as you focus on lowland areas (because those regions already have so many mosquitoes). That picture may change, however, as you move upward in elevation. Malaria has seen a dramatic upswing since the 1970s in highland cities like Nairobi (around 5,500 ft. above sea level). How much of that can be tied to temperature increases--as opposed to population movement, lapses in mosquito control or the spread of drug-resistant parasites--is a matter of debate. But because each year there are at least 300 million cases accounting for more than 1 million deaths, even a small uptick in the spread or severity of malaria could be devastating.